Drugs release post parenteral administration

Parenteral Drug Absorption and Injection Equipment

The video explains how medicines are absorbed after parenteral administration and reviews equipment used to give injections and intravenous (IV) fluids. It focuses on four routes: intradermal, subcutaneous, intramuscular, and intravenous. The depth of injection, blood supply to the site, and whether a medicine is formulated as a depot affect how quickly it is absorbed.

Intradermal (intracutaneous) injection

• Site: Dermis, just beneath the epidermis.
• Angle: About 5–15°.
• Absorption: The slowest route discussed, with limited entry into general circulation, partly because of blood flow at the site.
• Key feature: A small raised blister, or bleb, should form. The visible reaction makes this route useful for assessing responses.
• Uses: Allergy and tuberculin sensitivity tests, and local effects such as local anesthesia.
• Common sites: Upper chest, inner forearm, and upper back beneath the scapula.
• Equipment: A 1 mL syringe with a 26- or 27-gauge needle.

Subcutaneous injection

• Site: Fatty tissue beneath the skin.
• Volume: Usually less than 1 mL.
• Angle: About 45° with a longer needle, or 90° with a shorter needle, such as one used with an insulin pen.
• Common sites: Abdomen, outer upper arm, and front of the thigh.
• Absorption: Can be prolonged when the medicine is given as a depot formulation, which releases it over time.
• Equipment: A 1 mL syringe with a 23- or 25-gauge needle, or a prefilled multidose pen such as an insulin pen.

Intramuscular injection

• Site: Muscle.
• Angle: 90°.
• Absorption: Generally faster than subcutaneous injection because muscle has a richer blood supply. Depot formulations can still prolong the drug’s action.
• Capacity: Muscle can hold a larger volume than subcutaneous tissue.
• Equipment: A 3 or 5 mL syringe, depending on the volume, with a 20- or 25-gauge needle.

Intravenous injection and infusion

• Site: A peripheral or central vein.
• Angle: The video gives an insertion angle of about 25°.
• Absorption and action: Described as the fastest route because the drug enters the circulation directly.
• Methods:
  • Bolus: A dose given all at once or over a short period.
  • Infusion: A dose delivered into a vein over a longer period.

Infusion patterns

• Intermittent infusion: Given over more than five minutes but less than 24 hours; it may be repeated over several days. The video mentions both small volumes, such as 50 mL, and larger volumes of 250–1,000 mL.
• Continuous infusion: Fluid or medicine is delivered continuously.

IV Devices and Their Uses

Three-way stopcock

Used to give a bolus through an IV line while a patient is already receiving an infusion. It connects three tubes, and its handle controls which pathway is open or closed.

The video emphasizes checking the stopcock’s orientation: an incorrect setting could direct the drug into the infusion bottle instead of toward the patient.

Gravity infusion set

Used to deliver fluid from an IV container by gravity. Basic parts include a spike for the container, drip chamber, micron filter, sterile tubing, flow controller, connector, and protective cover.

Types of infusion set

• Microdrip (pediatric) set: 60 drops per mL; used when small, closely controlled volumes are needed.
• Macrodrip (adult) set: 20 drops per mL; delivers more fluid per drop and supports faster flow.
• Blood transfusion set: 15–20 drops per mL; includes filtration to remove clots and small aggregates.

IV cannula

A flexible tube inserted into the body to provide access for fluid or medication. A trocar or stylet helps puncture the tissue; after it is removed, the flexible cannula remains in place.

Cannulas are color-coded by size and flow rate, which helps distinguish them, particularly in emergencies.

Infusion pump

Controls the rate and volume of delivery. The video describes using a 25 or 50 mL syringe connected to the patient by a syringe-pump extension set. The extension set should be primed with isotonic fluid or the drug before connection.

Winged (butterfly) needle

Used for venipuncture, especially in superficial veins such as those in the hand or scalp. It has a needle, wings, flexible transparent tubing described as about 20–35 cm long, and a connector.

Its wings allow it to rest against the body surface and accommodate more patient movement than a straight needle.

Speaker and Source

• Speaker: One unnamed narrator/instructor; no other speakers are identified.
• Source: Department of Pharmacology & Therapy, FM-PHN UGM.